• 岡おか — hill / knoll
• 岡山おかやま — Okayama (place name)
• 岡目八目おかめはちもく — observer’s advantage / detached perspective
• 岡持おかもち — delivery container (for food)
• 岡引おかっぴき — Edo-period police assistant
• 岡惚おかぼれ — secret crush / one-sided love

The character 岡 combines the radical 山 (mountain) with a phonetic element, historically indicating a small rise or elevated ground — hence “hill / knoll.” It’s common in place names.